1. Field of the Invention
The present invention relates to a resin-sealed power semiconductor module, formed by transfer molding, which is excellent in terms of productivity. The present invention particularly relates to a resin-sealed power semiconductor module, formed by transfer molding, which is small in size and which realizes large-current operation.
2. Description of the Background Art
A power semiconductor module that is: small in size; capable of efficiently discharging heat generated by its operation, to the outside; and capable of operating with a large current, is a power semiconductor module sealed with resin by transfer molding.
One of such power semiconductor modules sealed with resin by transfer molding is the one in which: a power semiconductor element is mounted on one surface of a lead frame; a metal substrate that includes an aluminum plate or copper plate and includes a high thermal conductive insulation layer and a copper foil, is joined to the other surface of the lead frame; and these components are sealed with resin by transfer molding such that an aluminum plate surface or copper plate surface of the metal substrate is exposed.
In this power semiconductor module, plate-shaped terminals to be connected to external circuits protrude from peripheral side surfaces of the sealing resin of the transfer molding (see, e.g., Page 4 to 5, FIG. 1 of Japanese Laid-Open Patent Publication No. H11-204724 (hereinafter, referred to as Patent Document 1)).
Another power semiconductor module sealed with resin by transfer molding is the one in which: power semiconductor elements and terminals to be connected to external circuits are provided on a circuit pattern joined to a metal heat sink base; and these components are sealed with resin by transfer molding such that a surface of the heat sink base, which is the opposite surface to a surface having the circuit pattern formed thereon, is exposed.
In this power semiconductor module, terminals are joined to the circuit pattern so as to be substantially perpendicular to a surface of the circuit pattern. A surface of each terminal, which is opposite to a surface joined to the circuit pattern, is exposed at a surface of the transfer molding resin, which surface is in parallel to the surface of the circuit pattern.
Here, a cylinder having a screw hole, a resin-molded nut, and the like are used as terminals. Such terminals as the cylinder having a screw hole and the resin-molded nut are connected to external wiring via bolts (see, e.g., Page 7 to 9, FIGS. 2 and 6 of Japanese Laid-Open Patent Publication No. 2007-184315 (hereinafter, referred to as Patent Document 2)).
In the power semiconductor module sealed with resin by transfer molding, which is described in Patent Document 1, all the plate-shaped terminals protrude from the peripheral side surfaces of the transfer molding resin. Since a metal of each plate-shaped terminal is exposed, it is necessary to secure a sufficient insulation distance between the plate-shaped terminals.
Power semiconductor modules have a large number of terminals. For this reason, if a sufficient insulation distance is to be secured between the terminals of the power semiconductor module described in Patent Document 1 in which all the terminals protrude from the peripheral side surfaces of the transfer molding resin, the power semiconductor module becomes large-sized. This hinders size reduction of the power semiconductor module. This problem is particularly prominent in power semiconductor modules having a large number of terminals, or in power semiconductor modules having a large current carrying capacity and terminals with a large width.
In the power semiconductor module sealed with resin by transfer molding, which is described in Patent Document 2, terminals are cylinder-shaped terminals provided with holes. A cylinder having a screw hole, or a resin-molded nut, is used as a main terminal connected to a main circuit. That is, the main terminal is a terminal provided with a screw hole (hereinafter, referred to as a screw-fitted terminal). The screw-fitted terminal is connected to external wiring by a bolt.
A control terminal connected to a control circuit has a connector structure, and is connected to external wiring by a pin.
However, in the case where such a screw-fitted terminal is used as a main terminal connected to a main circuit of the power semiconductor module, it is necessary, when the current carrying capacity of the power semiconductor module is large, to connect multiple screw-fitted terminals to the main circuit in parallel, or to increase the diameter of a screw portion of the screw-fitted terminal. This also results in a large-sized power semiconductor module, and hinders size reduction of the power semiconductor module.
In the power semiconductor module described in Patent Document 1, the terminals protruding from the peripheral side surfaces of the transfer molding resin are present on the same plane. In other words, a terminal connected to a main circuit and a terminal connected to a control circuit have their plate surfaces on the same plane.
In the power semiconductor module described in Patent Document 2, the terminal connected to the main circuit and the terminal connected to the control circuit each have a surface with an opening that is positioned at one surface of the transfer molding resin.
The terminals of the power semiconductor modules described in Patent Documents 1 and 2 have such structures as above. Accordingly, in the case where different types of external circuits are connected to such a single power semiconductor module, a connecting process becomes complex. For example, the main terminal is connected to an external circuit via a bus bar substrate, cable, or the like that has a high current carrying capacity, and the control terminal is connected to an external circuit that is a printed circuit board. This causes low productivity.